Many wireless communication systems employ transceiver stations or radio heads to provide service within geographical service areas, where the boundaries of a service area are determined by the radio coverage of its associated transceiver station. Wireless service is provided to user equipment (UE) devices over radio frequency carriers (carriers) within each service area, where a carrier is the modulated waveform that conveys the physical channels as specified by the associated wireless technology standard. These service areas are sometimes referred to as “cells”.
Although the term “cell” sometimes refers to the geographical area where multiple uplink and downlink resources (e.g., pairs of uplink and downlink carriers) are used, increasingly the term “cell” is used to refer to the geographical service area where single uplink resource and a single downlink resource are used to communicate with the UE devices. For example, where Time Division Duplex (TDD) is used, a single frequency may be used for uplink and downlink at different times within the “cell”. Where Frequency Division Duplex (FDD) is used, a single uplink/downlink frequency pair (one uplink frequency and one downlink frequency) is used within a “cell”.
As discussed herein, one or more resources (carrier pairs) may be used in a service area. As a result, a service area may be a single cell or may contain multiple cells. In one common arrangement, each service area is adjacent to several other service areas to provide ubiquitous coverage over a large geographical area.
Adjacent service areas may overlap slightly, but, for the following discussion, no service areas provide service within the same geographical area. In many situations, there may be an advantage to dynamically change the configuration of the service areas, such as by selectively reducing the size of some service areas and expanding the size of one or more other service areas to provide service within the area previously serviced by the service areas that were reduced. Such dynamic coverage area configuration transitions may allow for more efficient operation of the system.
For example, a service area with only a small number of UE devices may be reduced to zero by deactivating its associated transceivers, and an adjacent service area that is serving several UE devices but has available capacity may be expanded to provide radio coverage for the UE devices previously contained in the reduced service area. Therefore, a service area that is reduced may be referred to as an energy saving service area since the energy consumed by its associated transceivers is reduced or eliminated, and a service area that is reduced to zero may be referred to as a deactivated service area. A service area that is expanded in cooperation with a service area that is reduced may be referred to as compensation service area since its service area is expanded to compensate for a service area that is reduced.
UE devices being served by an energy saving service area may lose their connection with the network if they are not handed over to another service area before the energy saving service area is deactivated. If the energy saving service area and the compensation service area operate on the same frequency resources, UE devices being served by an energy saving service area may lose their connection with the network if the compensation service area is expanded before the UE devices are handed over to another service area because of the interference between the energy saving service area and the compensation service area. As discussed below, management techniques are needed to control the dynamic coverage area configuration transitions.